The invention concerns non-anaphylactic forms of protein allergens and the use of the forms for hyposensitization and for determining antibodies (IgA, IgD, IgE, IgG, IgM) directed against the allergen, for instance in the context of diagnosing in vitro type I allergy (IgE mediated allergy). The invention also concerns a method for hyposensitization of a mammalian individual, typically a human individual, suffering from type I allergy against a protein allergen.
The invention primarily concerns treating and diagnosing humans.
By a protein allergen is meant any protein/polypeptide causing a type I mediated allergic reaction. Thus the term encompasses any naturally occuring protein allergen including the smallest fragments thereof that will cause a type I allergic reaction in a mammal, most importantly humans.
In April 1997, the present inventors have published an article dealing with non-anaphylactic fragments of the Bet v 1 allergen. See Vrtala et al., “Conversion of the major birch pollen allergen, Bet v 1, into two non-anaphylactic T cell epitope containing fragments”, J. Clin. Invest. 99(7) April 1997) 1673–1681.
Type I allergy represents a major health problem in industrialised countries where more than 20% of the population suffer from Type I allergic reactions (allergic rhinitis, conjunctivitis, allergic asthma and anaphylactic shock) (Kaplan (ed) Allergy. Churchill Livingstone, New York (1985)). Environmental proteins from pollen, mites and animal dander belong to the major components which induce release of biological mediators (e.g. histamine) by crosslinking effector cell (mast cell, basophil) bound specific IgE antibodies. The production of specific IgE from B-cells is stimulated by allergen specific T-helper cells which in their majority belong to the TH2 type (Romagnani, Immunol Today 13 (1992) 379–381). Therapy of Type I allergic diseases is currently performed by pharmacological treatment and by specific immunotherapy. Specific immunotherapy has been established already early in this century (Noon, Lancet 1 (1911) 1572–1573) and involves the systemic application of increasing doses of allergens for extended periods. Although specific immunotherapy is recognized as effective treatment, the occurrence of anaphylactic side effects represents one of the major disadvantages of this therapy. To reduce anaphylactic reactions the use of T-cell epitopes has recently been proposed for allergen specific immunotherapy (Briner et al., Proc. Natl. Acad. Sci. USA 90 (1993) 7608–7612, and Norman, Curr. Opin. Immunol 5 (1993) 986–973). Allergens harbour a great variety of different T-cell epitopes (Ebner et al., J. Immunol 150 (1993) 1047–1054; Joost-van-Neerven et al., J. Immunol. 151 (1993) 2326–2335; and Schenket al., J. Allergy Clin. Immunol. 96 (1995) 986–996) which may overlap with continuous IgE-epitopes. To prevent crosslinking of effector cell (mast cell, basophil) bound IgE and mediator release, T-cell epitopes and IgE epitopes need to be dissected. Following the concept of converting a major allergen into a T-cell vaccine we have selected Bet v 1 (Breiteneder et al., EMBO J. 8 (1989) 1935–1938), the major birch pollen allergen as a model. Bet v1 was selected because epitope analysis indicated that it forms conformational IgE epitopes (Visco et al., J. Immunol. 157 (1996) 956–962; and Laffer et al., J. Immunol. 157 (1996) 4953–4962). In addition Bet v1 represents one of the most common allergens which is recognized by 95% of tree pollen and food allergic individuals and almost 60% of them are sensitisized exclusively against Bet v1 (Jarolim et al., Allergy 44 (1989) 385–394). The cDNA coding for Bet v1 has recently been isolated (Breitenederet al., EMBO J. 8 (1989) 1935–1938) and recombinant Bet v1 was expressed in Escherichia coli (Valenta et al., J. Allergy Clin. Immunol. 88 (1991) 889–894; and Ferreira et al., J. Biol. Chem. 268 (1993) 19574–19580). Recombinant Bet v1 has been shown to possess similar IgE-binding capacity as natural Bet v1 and shares IgE as well as T-cell epitopes with Bet v1 homologous proteins present in pollen from various trees and plant derived foods (Ebner et al., J. Allergy Clin Immunol. 95 (1995) 962–969; Ebner et al., J. Immunol 150 (1993) 1047–1054; and Schenk et al., Eur. J. Biochem. 224 (1994) 717–724). The biological activity of the recombinant Bet v1 has been demonstrated by histamine release experiments and by skin prick testing of allergic patients (Valenta et al., J. Allergy Clin. Immunol. 91 (1993) 88–97; Pauli et al., J. Allergy Clin. Immunol. 98 (1996) 1100–1109; and Menz et al., Clin. Exp. Allergy 26 (1995) 50–60).